Expression, immune infiltration and clinical significance of SPAG5 in hepatocellular carcinoma: A gene expression-based study.

Background: Overexpression of sperm-associated antigen 5 (SPAG5) is a marker of poor prognosis in numerous tumors and is recognized as an index of tumor proliferation; however, its expression in liver cancer remains unclear.
Methods: The Oncomine (https://www.oncomine.org) and Timer (https://cistrome.shinyapps.io/timer) databases were used to analyze the expression of SPAG5 in liver hepatocellular carcinoma (HCC) and normal liver tissues. The relationship between the expression of SPAG5 and immune infiltration of HCC was investigated using the Timer and GEPIA (http://gepia.cancer-pku.cn) databases, and the mechanism was analyzed using Gene Set Enrichment Analysis. A Kaplan-Meier Plotter (http://kmplot.com/analysis) was used to evaluate the effect of SPAG5 on the prognosis of patients with HCC.
Results: The results revealed that the SPAG5 expression level was positively correlated with the infiltration levels of CD8 ⁺ T cells, macrophages, neutrophils, and especially B cells and dendritic cells. In addition, SPAG5 expression was significantly associated with T cell exhaustion. The overall survival time, progression-free survival time, recurrence-free survival time and disease-specific survival time were significantly reduced for HCC patients with high SPAG5 expression (p < 0.01) and high expression of SPAG5 was significantly associated with a poor overall survival time and progression-free survival time of grade and stage II-III HCC (p < 0.05) but not with stage I HCC (p > 0.05). Additionally, the expression of SPAG5 is related to the p53 and cell cycle signal pathways.
Conclusions: In conclusion, SPAG5 is not only a marker of immune infiltration and poor prognosis, but also a potential therapeutic target for liver cancer.
(© 2019 John Wiley & Sons, Ltd.)